Applies - in contrast to parts 1 and 2 which deal with full-voltage and star-delta starters - to those performing electrical operation by cutting out resistors inserted in the rotor circuit after reaching normal speed, and which are intended for use up to 1000 V a.c., including two-direction starters and the resistors themselves. All common items of part 1 are applicable if not specified otherwise in this part, i.e. clauses concerning definitions, characteristics, service and construction conditions, and tests. Excluded are the breaking of short-circuit currents, equipment with unbalanced values in the three phases, equipment for speed adjustment, liquid and semi-conductor starters.